International Publication No. WO88/10422 discloses, inter alia, techniques for analysing carbohydrate structures or distinguishing or separating carbohydrate substances, involving applying carbohydrate substances to an electrophoretic gel and running the gel to cause differential migration of different substances. The carbohydrate substances may be pre-labelled with a fluorescent labelling reagent, e.g. amino fluorescein, to impart a charge to the substance, thereby to enable electrophoretic separation, and to enable visualisation of the substances after running of the gel. In this case, visualisation may be effected with the naked eye, but enhanced sensitivity is obtained by viewing with a charge coupled device (CCD).
The present invention concerns a development of such techniques, and is based on the discovery that unexpectedly good results can be obtained by using naphthalene derivatives as the fluorescent labelling reagent.